Research And Implementation Of Hardware Scheme Of Indoor Positioning System Based On TDOA

Indoor positioning technology based on user location information has been widely applied in fields such as smart logistics and indoor navigation,and related technologies are currently a research hotspot in the industry.The current mainstream indoor positioning technologies such as Wi Fi,Bluetooth,and Ultra Wide-band have their own characteristics in terms of positioning accuracy,penetration,coverage,power consumption,and cost,and each technology has its own specific application scenarios.This thesis focuses on the indoor positioning requirements of sub meter level positioning accuracy,good penetration,wide coverage,and low power consumption,and studies the sub meter level distance difference measurement method and hardware implementation scheme based on asynchronous Time Difference of Arrival for low-power indoor applications.The main research content of the thesis is as follows:Firstly,this thesis provides a brief overview of indoor and outdoor positioning technology,with a focus on researching and summarizing the current research status of indoor positioning technology and TDOA positioning technology at home and abroad.It summarizes the characteristics of mainstream solutions and the problems they face in response to the requirements addressed in this thesis,and proposes the significance and ideas of this research topic.Secondly,this thesis studies the structure and model of the TDOA positioning system,and studies an asynchronous TDOA positioning model based on dual antenna base stations,fundamentally solving the problem of difficult clock synchronization between base stations and the introduction of time difference measurement errors in traditional TDOA positioning models,reducing the difficulty of system implementation.The structure design of the asynchronous TDOA positioning system is carried out,and the hardware circuit implementation scheme is studied and implemented.Subsequently,this thesis studies the accurate measurement of distance difference based on the proposed dual antenna base station asynchronous TDOA positioning model.Based on the generalized cross correlation method for calculating time delay,the intermediate frequency beat frequency processing method and a "two rulers" measurement method are innovatively proposed at the receiving end.Using narrowband signals based on low-power indoor wireless networks with a bandwidth of no more than 500 k Hz,the measurement accuracy of the distance difference between the target node and the two antennas of the base station can still reach the sub meter level when the signal-to-noise ratio is as low as-10 d B.Finally,on the hardware experimental device built on the software defined radio platform,FPGA based logic design and ARM based embedded programming are carried out to achieve wireless ranging signal transmission and reception experiments.The proposed distance difference measurement scheme is verified through physical testing and achieved the expected results.